1. Field of the Invention
The present invention relates to an IC card and a method of manufacturing the same, and more particularly, to an IC card in which an antenna circuit pattern and a contact circuit board of a combi-chip provided in the IC card are directly connected so that an electric resistance therebetween is reduced, and a method of manufacturing the same.
2. Description of the Related Art
IC cards refer generally to cards on which IC chips are mounted and can be used as electronic identification (ID) cards, license cards, electronic money, and credit cards with various information stored in the IC chips. The term “IC card” used herein is intended to include “Smart card”, “Chip card”, and “Memory card”, etc. as typically used in commerce. For example, by providing personal information such as address, name, citizenship registration number (or ID number), driver's license number, and medical insurance number in an IC chip, the IC card can be used as an electronic ID card. In another example, the IC card can be used as electronic money with bank deposit information stored in a chip so that, for example, purchase payments at stores are possible without using cash, rather by accessing the bank deposit information of a user and deducting purchase prices from the bank deposit account. In yet another example, a certain amount of money is charged as electronic money and a subway fare or electric railway fair is deducted from the electronic money amount.
The IC card can typically be classified into a contact type and a non-contact type based upon the method of communication between the IC card and a terminal. A contact type IC card performs a predetermined operation as a contact terminal formed on the IC card contacts a contact terminal of the external terminal. However, in a non contact type IC card, communications between the IC card and an external terminal is carried out using a radio frequency (RF). The non-contact type IC card uses an RF of a high frequency or lower frequency for the communications.
On the other hand, a combi-type IC card (or Combi Card) typically has a low frequency RF chip module and a combi-chip module. The combi-chip module can perform communications in a contact type method or using a high frequency RF. Thus, the combi-type IC card can perform communications in the contact type method and using a low or high RF.
FIG. 1 is a sectional view illustrating a typical combi-type IC card. Referring to the drawing, a combi-type IC card includes a low frequency chip module 21 and a combi-chip module 16. The low frequency chip module 21 is arranged adjacent to the center of the card while the combi-chip module 16 is arranged adjacent to a lateral side of the card. The low frequency chip module 21 and the combi-chip module 16 are respectively embedded in the first and second dielectric layers 11 and 12 attached to each other. Upper and lower protective layers 13 and 14 are provided on an upper surface of the first dielectric layer 11 and a lower surface of the second dielectric layer, respectively. A cover layer 15 is disposed beneath the lower protective layer 14. Also, a hologram 23 can be attached on one side of the surface of the upper protective layer 13.
A low frequency antenna pattern 24 of the low frequency chip module 21 is arranged on a film 21a supporting the low frequency chip module 21 and is embedded between the first and second dielectric layers 11 and 12. The low frequency chip module 21 is arranged preferably at a central portion of the card. Thus, the low frequency antenna pattern 24 is disposed in a loop form around the central portion of the card.
A high frequency antenna pattern 18 provided at the combi-chip module 16 is formed before the combi-chip module 16 is inserted within a hole in the first and second dielectric layers 11 and 12. When the combi-chip module 16 is inserted in a hole 27 (FIG. 2D) formed in the first and second dielectric layers 11 and 12 by a milling process, the high frequency antenna pattern 18 is electrically connected to an antenna connect pad (not shown) of the combi-chip module 16 via a conductive paste (not shown). The high frequency antenna pattern 18 is disposed about the peripheral portion of the card.
FIGS. 2A through 2E are sectional views illustrating steps of manufacturing the IC card shown in FIG. 1. Referring to FIG. 2A, the first and second dielectric layers 11 and 12, the low frequency chip module 21 to be embedded between the first and second dielectric layers 11 and 12, and the upper and lower protective layers 13 and 14 are provided. A hole 11a in which the low frequency chip module 21 is to be inserted is formed in advance in the first dielectric layer 11. The low frequency chip module 21 is provided in a module in which the low frequency antenna 24 is disposed on a support film 25.
Also, it can be seen that the high frequency antenna 18 is disposed between the upper protective film 13 and the first dielectric layer 11 before the combi-chip module is provided thereto.
Referring to FIG. 2B, all elements shown in FIG. 2A are assembled. As a chip of the low frequency chip module 21 is inserted in the hole 11a of the first dielectric layer 11, the low frequency chip module 21 is embedded between the first and second dielectric layers 11 and 12. Also, the low frequency antenna 24 is embedded between the first and second dielectric layers 11 and 12. The high frequency antenna 18 is embedded between the first dielectric layer 11 and the upper protective layer 13.
Referring to FIG. 2C, a hologram 23 is attached to one side of an upper surface of the upper protective film 13.
Referring to FIG. 2D, a hole 27 in which the combi-chip module is to be inserted is formed. The hole 27 is formed, for example, by milling relevant portions of the upper protective layer 13, the first dielectric layer 11, and the second dielectric layer 12. Part of the high frequency antenna 18 is exposed by removing the area of the hole 27 in the upper protective layer 13 greater than that of the hole 27 in the first and second dielectric layers 11 and 12.
Referring to FIG. 2E, a conductive paste 28 is coated on an exposed portion of the high frequency antenna 18.
FIG. 2F illustrates the combi-chip module 16.
Referring to FIG. 2G, the combi-chip module 16 shown in FIG. 2F is assembled by inserting in the hole 27. The combi-chip module 16 itself is attached to the card through an adhesive portion 29. An antenna contact pad (not shown) provided in the combi-chip module 16 is electrically connected to the high frequency antenna 18 via the conductive pad 28.
In the above IC card, since the high frequency antenna 18 and the antenna contact pad of the combi-chip module 16 are electrically connected using the conductive paste, the electrical resistance of the conductive paste increases. That is, since the conductive paste includes a conductive component and a binder, the resistance thereof increases due to a low density of the conductive component. The resistance is further increased as the volume of the conductive component is reduced by reaction of a high molecular substance of the binder. Also, since the pad is oxidized by a solvent component, the resistance of the pad is further increased. As a result, the length of recognizing a high frequency signal is shortened. The conductive paste is a mixture of a plastic component exhibiting a high degree of hardness and conductive particles exhibiting no adhesiveness, and thus, the conductive paste is weak at mechanical deformation such as bending and cracks or a short circuit is easily generated. Furthermore, since the chip module and the external contact pad are disposed in a card having a limited thickness, it is difficult to manufacture the contact pad and the chip module having a desired strength and durability. Also, additional processes for manufacturing the chip module and assembling the same are needed.